Led light bar and backlight module

ABSTRACT

A light-emitting diode light bar includes a printed circuit board and a light-emitting diode. The printed circuit board has a protective layer, a first signal line, and a first extension line. The LED is disposed on the first signal line and the first extension line. The protective layer is formed above the first signal line and the first extension line, and has an opening that exposes a portion of the first signal line, and a portion of the extension line, such that a first exposed length of the first signal line is substantially equal to a second exposed length of the first extension line.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number100130730, filed Aug. 26, 2011, which is herein incorporated byreference.

TECHNICAL FIELD

The present disclosure generally relates to a light bar and a backlightmodule having the light bar. More particularly, the present disclosurerelates to a light-emitting diode light bar and a backlight modulehaving the light-emitting diode (LED) light bar.

BACKGROUND

Currently, light-emitting diodes (LEDs) are widely used in a backlightmodule for a liquid crystal display. The quantity of the light-emittingdiodes is decreased to reduce the manufacture cost of the liquid crystaldisplay, thus resulting in a larger gap between two adjacent LEDs.Therefore, the optical design and assembling precision of the backlightmodule are more and more challenging. One of the key factors is toprecisely align the LEDs in the vertical direction of the backlightmodule.

Nowadays, the LEDs are fixed on a printed circuit board (PCB) of a lightbar with the surface mounting technology (SMT). First, a solder paste isprinted on the soldering pads of the printed circuit board. Second, theLEDs are placed on the soldering pads having the solder paste. Finally,the LEDs are fixed on the soldering pads by heating with a reflowfurnace. However, even through the LEDs can be precisely placed on thesoldering pads initially, yet portions of the signal lines connected andadjacent to the soldering pads are exposed without being covered by thesolder mask layer of the PCB, the molten solder will be easilydistributed fully on the exposed areas due to its surface tensionproperty, thus causing the LEDs to be deviated from the originaladhering positions on the soldering pads, also affecting the alignmentprecision of the LEDs in the vertical direction of the backlight module.

Therefore, there is a need to improve the alignment position of the LEDsin the vertical direction of the backlight module.

SUMMARY

One objective of the embodiments of the present invention is to providea LED light bar of which light-emitting diodes can be precisely alignedto the soldering pads of a printed circuit board to effectively ensurepositions of the LEDs in the vertical direction of the backlight module.

To achieve these and other advantages and in accordance with theobjective of the embodiments of the present invention, as the embodimentbroadly describes herein, the embodiments of the present inventionprovides a light emitting diode light bar including a printed circuitboard (PCB) and a light-emitting diode. The printed circuit boardincludes a protective layer, a soldering pad, a first signal line, and afirst extension line. The soldering pad is formed on the printed circuitboard, and has a first side and a second side opposite to the firstside. The first signal line is connected to the first side of thesoldering pad, and the first extension line is connected to the secondside of the soldering pad. The protective layer is formed on the firstsignal line and the first extension line, and has an opening to exposethe soldering pad, a portion of the first signal line and a portion ofthe first extension line. The first signal line has a first exposedlength and the first extension line has a second exposed length. Thesecond exposed length is substantially equal to the first exposedlength.

The first extension line is aligned with the first signal line. Thefirst signal line has a first exposed width and the first extension linehas a second exposed width. The second exposed width is substantiallyequal to the first exposed width. In addition, the first signal line andthe first extension line are coplanar. The first signal line and thefirst extension line are collinear.

In one embodiment, the printed circuit board may further include asecond signal line and a second extension line. The second signal lineis connected to a third side of the soldering pad, and the second signalline has a third exposed length. The second extension line is connectedto a fourth side of the soldering pad opposite to the third side. Thesecond extension line has a fourth exposed length. The fourth exposedlength is substantially equal to the third exposed length.

In addition, the second signal line is vertical to the first signalline. The second extension line is aligned with the second signal line.The second signal line has a third exposed width, and the secondextension line has a fourth exposed width, and the fourth exposed widthis substantially equal to the third exposed width. The second signalline and the second extension line are coplanar.

Alternatively, the light emitting diode light bar can include a printedcircuit board (PCB) and a light-emitting diode. The printed circuitboard further includes a first signal line, a first extension line and aprotective layer formed above the first signal line and the firstextension line. The protective layer has an opening to expose a portionof the first signal line and a portion of the first extension line, andthe portion of the first signal line is symmetrical to the portion ofthe first extension line with a symmetrical axis. The light-emittingdiode is fixed on the first signal line and the first extension line.The first signal line has a first exposed width and the first extensionline has a second exposed width, and the second exposed width issubstantially equal to the first exposed width. The first signal linehas a first exposed length and the first extension line has a secondexposed length, the second exposed length is substantially equal to thefirst exposed length. In addition, the first extension line can beformed by a plurality of extension strips, and the first signal line andthe first extension line are coplanar. A lead of the light-emittingdiode can be a V-shaped lead, a U-shaped lead or an I-shaped lead.

In addition, another embodiment according to the present invention is toprovide a backlight module having the foregoing light emitting diodelight bar, a light guide plate and a reflector. The light-emitting diodeof the light emitting diode light bar has a first central axis, and thelight guide plate is disposed adjacent to the light emitting diode lightbar and has a second central axis. The position of the light-emittingdiode connected to the soldering position on the soldering pad can beadjusted by using the extension line, thereby aligning the first centralaxis with the second central axis.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will be more readily appreciated as the same becomes betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a partial top view of a LED light bar according to afirst embodiment of the present invention;

FIG. 2 illustrates a top view of a LED light bar according to a secondembodiment of the present invention;

FIG. 3 illustrates a top view of a LED light bar having an L-shapedsoldering pad according to the present invention;

FIG. 4 illustrates a cross-sectional view of a backlight moduleaccording to the present invention;

FIG. 5 illustrates a top view of a LED light bar according to a furtherembodiment of the present invention; and

FIG. 6 illustrates a top view of a LED and a print circuit board of aLED light bar according to a still further embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is of the best presently contemplated mode ofcarrying out the present disclosure. This description is not to be takenin a limiting sense but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined by referencing the appended claims.

Refer to FIG. 1. FIG. 1 illustrates a partial top view of a LED lightbar according to a first embodiment of the present invention. The LEDlight bar 100 includes a printed circuit board (PCB) 110 and alight-emitting diode 160 (for conveniently explaining the structure ofthe printed circuit board 110, the position of the light-emitting diode160 is merely depicted by a dashed line), the printed circuit board 110further includes a soldering pad 120, a solder mask layer 130, a firstsignal line 140, and a first extension line 150 for tension balance.Generally, the light-emitting diode 160 is fixed on the soldering pad120 with solder and the light-emitting diode 160 can cover a partialarea of the soldering pad 120 as illustrated in FIG. 2, but not limitedto it.

The soldering pad 120, the first signal line 140 and the first extensionline 150 for tension balance are formed by etching a metal layer on theprinted circuit board 110, and are formed in the same layer on theprinted circuit board (PCB) 110. The metal layer is made of, forexample, copper. The soldering pad 120 is a rectangle or square, and hasa first side 122 and a second side 124 opposite to the first side 122 inthe vertical direction (Z-axis). The first signal line 140 is connectedto the first side 122 for electrically connecting the soldering pad 120to a power source or any other electrical device for providingelectronic signals to the light-emitting diode 160 through the firstsignal line 140 and the soldering pad 120. The first extension line 150for tension balance is connected to the second side 124 to balance thesurface tension of a molten solder in the SMT process, and therefore thefirst extension line 150 for tension balance can only be connected tothe soldering pad 120 and no other electrical components are connectedto the first extension line 150. In this embodiment, the first extensionline 150 for tension balance is aligned with the first signal line 140along the Z-axis. For example, the first extension line 150 for tensionbalance and the first signal line 140 are collinear. In other words, theextensive direction of the first extension line 150 and the first signalline 140 are collinear. However, in another embodiment, the firstextension line 150 for tension balance can be connected to any point ofthe second side 124 of the soldering pad 120. The solder mask layer 130,i.e. a protective layer, is formed on the first signal line 140 and thefirst extension line 150, and partially covers the first signal line 140and the first extension line 150. The solder mask layer 130 has anopening 132 positioned corresponding to the soldering pad 120 to exposethe soldering pad 120 for soldering the light-emitting diode 160thereon.

The opening 132 of the solder mask layer 130 can not only expose thesoldering pad 120 but also expose a portion of the first signal line 140and a portion of the first extension line 150 for tension balance. Theportion of the first signal line 140 exposed in the opening 132 has afirst exposed metal length L1 and a first exposed metal width W1. Thefirst exposed metal length L1 is a length of the first signal line 140extending from the edge of the opening 132 of the solder mask layer 130to the first side 122 of the soldering pad 120. The first exposed metalwidth W1 is a width of the first signal line 140 within the opening 132of the solder mask layer 130. The portion of the first extension line150 exposed in the opening 132 has a second exposed metal length L2 anda second exposed metal width W2. The second exposed metal length L2 is alength of the first extension line 150 extending from the edge of theopening 132 of the solder mask layer 130 to the second side 124 of thesoldering pad 120. The second exposed metal width W2 is a width of thefirst extension line 150 within the opening 132 of the solder mask layer130.

In a surface mounting technology (SMT) process for fixing thelight-emitting diode 160 on the soldering pad 120, the molten soldertends to concentrate on the exposed sheet metal due to the surfacetension thereof. In this embodiment, the second exposed metal length L2of the first extension line 150 for tension balance is substantiallyequal to a first exposed metal length L1 of the first signal line 140,that is, the exposed metal lengths of the exposed sheet metals besidethe soldering pad 120 are substantially equal in the vertical direction(Z-axis). Therefore, the surface tension of the molten solder on theexposed sheet metal can be balanced in the vertical direction (Z-axis),so that the light-emitting diode 160 can be exactly aligned with thesoldering pad 120.

In addition, symmetrical and equal exposed areas of the exposed sheetmetals beside the soldering pad in the vertical direction (Z-axis) canfurther ensure the surface tension balance thereof. For example, notonly the first exposed metal length L1 is substantially equal to thesecond exposed metal length L2, but also the first exposed metal widthW1 is substantially equal to the second exposed metal width W2.

Refer to FIG. 2. FIG. 2 illustrates a top view of a LED light baraccording to a second embodiment of the present invention. The firstsignal line 240 and the first extension line 250 for tension balance aresimilar to those of the first embodiment and are respectively connectedto the first side 222 and the second side 224 opposite to the first side222 of the soldering pad 220 in the vertical direction (Z-axis). In thisembodiment, the printed circuit board 210 has an additional conductiveline. That is, the soldering pad 220 has a third side 226 and a fourthside 228 opposite to the third side 226 in the horizontal direction(X-axis). The second signal line 242 is connected to the third side 226,and is substantially vertical to the first signal line 240, andtherefore the second signal line 242 can electrically connect thesoldering pad 220 to a power source or any other electrical device forproviding electronic signals to the light-emitting diode 260 through thesecond signal line 242 and the soldering pad 220. The second extensionline 252 is connected to the fourth side 228 to balance the surfacetension of the molten solder in the SMT process, and the secondextension line 252 is not necessary to be electrically connected to anyother addition electrical device. In one embodiment, the secondextension line 252 for tension balance is preferably aligned with thesecond signal line 242 in the X-axis. Furthermore, the second extensionline 252 for tension balance can also be connected to any other pointalong the fourth side 228 of the soldering pad 220.

The opening 232 of the solder mask layer 230 can expose a portion of thefirst signal line 240, a portion of the first extension line 250 fortension balance, a portion of the second signal line 242 and a portionof the second extension line 252 for tension balance. The portion of thefirst signal line 240 has a first exposed metal length L1 and a firstexposed metal width W1. The first exposed metal length L1 is a length ofthe first signal line 240 extending from the edge of the opening 232 ofthe solder mask layer 230 to the first side 222 of the soldering pad220. The first exposed metal width W1 is a width of the first signalline 240 within the opening 232 of the solder mask layer 230. Theportion of the first extension line 250 for tension balance has a secondexposed metal length L2 and a second exposed metal width W2. The secondexposed metal length L2 is a length of the first extension line 250 fortension balance extending from the edge of the opening 232 of the soldermask layer 230 to the second side 224 of the soldering pad 220. Thesecond exposed metal width W2 is a width of the first extension line 250for tension balance within the opening 232 of the solder mask layer 230.

The portion of the second signal line 242 has a third exposed metallength L3 and a third exposed metal width W3. The third exposed metallength L3 is a length of the second signal line 242 extending from theedge of the opening 232 of the solder mask layer 230 to the third side226 of the soldering pad 220. The third exposed metal width W3 is awidth of the second signal line 242 within the opening 232 of the soldermask layer 230. The portion of the second extension line 252 for tensionbalance has a fourth exposed metal length L4 and a fourth exposed metalwidth W4. The fourth exposed metal length L4 is a length of the secondextension line 252 extending from the edge of the opening 232 of thesolder mask layer 230 to the fourth side 228 of the soldering pad 220.The fourth exposed metal width W4 is a width of the second extensionline 252 for tension balance within the opening 232 of the solder masklayer 230.

In this embodiment, besides the second exposed metal length L2 of thefirst extension line 250 is substantially equal to the first exposedmetal length L1 of the first signal line 240, and the fourth exposedmetal length L4 of the second extension line 252 is substantially equalto the third exposed metal length L3 of the second signal line 242. Thatis, the exposed sheet metals beside the soldering pad 220 havesubstantially equal exposed metal lengths in the Z-axis. In addition,the exposed sheet metals beside the soldering pad 220 have substantiallyequal exposed metal lengths in the X-axis. Therefore, the surfacetensions of the molten solder can be balanced not only in the Z-axis butalso in the X-axis so that the light-emitting diode 260 can effectivelyaim at the soldering pad 220.

In addition, symmetric and equal areas of the exposed sheet metal besidethe soldering pad 220 along the X-axis can further ensure the surfacetension balance for the molten solder. For example, the third exposedmetal length L3 is substantially equal to the fourth exposed metallength L4, and as well the third exposed metal width W3 is substantiallyequal to the fourth exposed metal width W4.

The soldering pads of the foregoing embodiments are rectangularsoldering pads or square soldering pads. However, a different shapesoldering pad design for another LED light bar 300 is provided to fitthe different terminals of the light-emitting diodes. Refer to FIG. 3.The soldering pad 320 can be L-shaped. The soldering pad 320 is formedon the printed circuit board 310, and has a first side 322 and a secondside 324 opposite to the first side 322 along the vertical direction(Z-axis), and has a third side 326 and a fourth side 328 along thehorizontal direction (X-axis). The first signal line 340 is connected tothe first side 322, a first extension line 350 for tension balance isconnected to the second side 324, and a second signal line 342 isconnected to the third side 326, and the second extension line 352 fortension balance is connected to the fourth side 328. The first signalline 322 and the second signal line 342 are used to connect thesoldering pad 320 to the power source or any other electrical device forproviding electronic signals to the light-emitting diode 360 through thefirst signal line 322 and the soldering pad 320. The first extensionline 350 and the second extension line 352 can effectively balance thesurface tension of the molten solder in the SMT process and are notnecessary to be electrically connected to any additional device.

An opening 332 of a solder mask layer 330 exposes a portion of the firstsignal line 340, a portion of the second signal line 342, a portion ofthe first extension line 350 for tension balance and a portion of thesecond extension line 352 for tension balance. The portion of the firstsignal line 340 has a first exposed metal length L1 and a first exposedmetal width W1. The portion of the first extension line 350 for tensionbalance has a second exposed metal length L2 and a second exposed metalwidth W2, and the portion of the second signal line 342 has a thirdexposed metal length L3 and a third exposed metal width W3, and theportion of the second extension line 352 for tension balance has afourth exposed metal length L4 and a fourth exposed metal width W4.

In addition, the second exposed metal length L2 of the first extensionline 350 is substantially equal to the first exposed metal length L1 ofthe first signal line 340. The fourth exposed metal length L4 of thesecond extension line 352 is substantially equal to the third exposedmetal length L3 of the second signal line 342. Therefore, the surfacetension of the molten solder can be balanced in the Z-axis and in theX-axis to effectively align the light-emitting diode 360 with thesoldering pad 320.

The foregoing LED light bar having the extension lines for tensionbalance can be further used in the backlight module. For example, asshown in FIG. 4, a backlight module 40 includes a LED light bar 400, alight guide plate 500 disposed adjacent to the LED light bar 400, areflector 600 disposed under the light guide plate 500, and an opticalfilm module 700 disposed above the light guide plate 500. The LED lightbar 400 includes a printed circuit board 410 having the extension linesfor tension balance and a light-emitting diode 460. The light-emittingdiode 460 has a first central axis C1, e.g. the central normal line of alight emitting surface 462 of the light-emitting diode 460. The firstcentral axis C1 is vertically disposed around one half of the height ofthe light-emitting diode 460 (along the Z-axis). In addition, the lightguide plate 500 has a second central axis C2, e.g. the central normalline of a light incident surface 502 of the light guide plate 500. Thesecond central axis C2 is vertically disposed around one half of theheight of the light guide plate 500 (along the Z-axis). The extensionlines for tension balance according to the present disclosure caneffectively adjust the position of the light-emitting diode 460 on thesoldering pad of the printed circuit board 410 to align the firstcentral axis C1 with the second central axis C2, thereby exactlypositioning the light-emitting diode 460 on the backlight module 40 inthe vertical direction (Z-axis).

Refer to FIG. 5. FIG. 5 illustrates a top view of a LED light baraccording to a further embodiment of the present invention. The firstsignal line 840 and the first extension line 850 for tension balance aresimilar to those of the first embodiment and are respectively connectedto the first side 822 and the second side 824 opposite to the first side822 of the soldering pad 820 in the vertical direction (Z-axis). Thefirst extension line 850 is not necessary to be electrically connectedto any other addition electrical device. In one embodiment, the firstextension line 850 for tension balance is aligned with the first signalline 840. For example, the first extension line 850 for tension balanceand the first signal line 840 are collinear.

The opening 832 of the solder mask layer 830 can expose a portion of thefirst signal line 840, a portion of the first extension line 850 fortension balance. The portion of the first signal line 840 has a firstexposed metal length L1 and a first exposed metal width W1. The firstexposed metal length L1 is a length of the first signal line 840extending from the edge of the opening 832 of the solder mask layer 830to the first side 822 of the soldering pad 820. The first exposed metalwidth W1 is a width of the first signal line 840 within the opening 832of the solder mask layer 830. The portion of the first extension line850 for tension balance has a second exposed metal length L2 and asecond exposed metal width W2. The second exposed metal length L2 is alength of the first extension line 850 for tension balance extendingfrom the edge of the opening 832 of the solder mask layer 830 to thesecond side 824 of the soldering pad 820. The second exposed metal widthW2 is a width of the first extension line 850 for tension balance withinthe opening 832 of the solder mask layer 830. In this embodiment, theportion of the first extension line 850 for tension balance issymmetrical to the portion of the first signal line 840 with asymmetrical axis 801. The symmetrical axis 801 means the middle linecrosses through the opening 832 along the X axis. For example, thesecond exposed metal length L2 of the first extension line 850 issubstantially equal to the first exposed metal length L1 of the firstsignal line 240, and the second exposed metal width W2 of the firstextension line 850 for tension balance is substantially equal to thefirst exposed metal width W1 of the first signal line 840 within theopening 832 of the solder mask layer 830. In another embodiment, thesymmetrical axis 801 is the middle line crosses through the opening 832along the Z axis. The first extension line 850 and first signal line 840are exposed in the different side of the symmetrical axis 801, but notlimited to it. For example, the symmetrical axis 801 can be a diagonalline crosses through the opening 832.

In addition, the first extension line 850 can be formed by a pluralityof extension strips. As FIG. 6 shown, the first extension line 850 hasthe first extension strip 851, the second extension strip 852 and thethird extension strip 853, but not limited to it. For example, the firstextension line 850 has the two or more than two extension strips. Inthis embodiment, the second exposed metal width W2 is calculated fromthe first extension strip 851 to the third extension strip 853. That isto say, the second exposed metal width W2 is equal to the sum of thewidth of the extension strips and the gap between extension strips. Forexample, the second exposed metal width W2 is sum of the width of thefirst extension strip 851, the width of the second extension strip 852,the width of the third extension strip 853, the gap between the firstextension 851 and the second extension 852 and the gap between thesecond extension 852 and the third extension 853. In this embodiment,the second exposed metal width W2 of the first extension line 850 withinthe opening 832 of the solder mask layer 830 is also substantially equalto the first exposed metal width W1 of the first signal line 840 withinthe opening 832 of the solder mask layer 830. Further, the first signalline 840 and the first extension line 850 are coplanar. In addition, thefirst signal line 840 and the first extension line 850 are collinear. Inother words, a plurality of the extension strips 851, 852, 853 areindividually collinear with the first signal line 840.

As FIG. 5 shown, the widths of the extension strips 851, 852, 853 arethe same, but not limited to it. For example, the width of the firstextension strip 851 is bigger than the width of the second extensionstrip 852 and the width of the second extension strip 852 is bigger thanthe width of the third extension strip 853. As the second exposed metalwidth W2 is satisfied with the first exposed metal width W1, the varietyof width of the extension strips is accepted.

Refer to FIG. 6. FIG. 6 illustrates a top view of a LED and a printcircuit board of a LED light bar according to a still further embodimentof the present invention. In this embodiment, the LED light bar 900includes a printed circuit board (PCB) 910 and a light-emitting diode960. The printed circuit board 910 further includes a solder mask layer930, a first signal line 940, and a first extension line 950 for tensionbalance.

The first signal line 940 and the first extension line 950 for tensionbalance are formed by etching a metal layer on the printed circuit board910, and are formed in the same layer on the printed circuit board (PCB)910, i.e. the first signal line 940 and the first extension line 950 arecoplanar. The metal layer is made of, for example, copper.

The light-emitting diode 960 is fixed on the first signal line 940electrically connecting to a power source or any other electrical devicefor providing electronic signals to the light-emitting diode 960 throughthe first signal line 940. The solder mask layer 930, i.e. a protectivelayer, is formed on the first signal line 940 and the first extensionline 950, and partially covers the first signal line 940 and the firstextension line 950. The solder mask layer 930 has an opening 932 toexpose the first signal line 940 and a portion of the first extensionline 950 for soldering the light-emitting diode 960 thereon.

The opening 932 of the solder mask layer 930 can expose a portion of thefirst signal line 940 and a portion of the first extension line 950 fortension balance. The portion of the first signal line 940 exposed in theopening 932 has a first exposed metal length L1 and a first exposedmetal width W1. The first exposed metal length L1 is a length of thefirst signal line 940 extending from the edge of the opening 932 of thesolder mask layer 930. The first exposed metal width W1 is a width ofthe first signal line 940 within the opening 932 of the solder masklayer 930. The portion of the first extension line 950 exposed in theopening 932 has a second exposed metal length L2 and a second exposedmetal width W2. The second exposed metal length L2 is a length of thefirst extension line 950 extending from the edge of the opening 932 ofthe solder mask layer 930. The second exposed metal width W2 is a widthof the first extension line 950 within the opening 932 of the soldermask layer 930.

In this embodiment, the portion of the first extension line 950 fortension balance is symmetrical to the portion of the first signal line940 with a symmetrical axis 901. The symmetrical axis 901 means themiddle line crosses through the opening 932 along the X axis. Forexample, the second exposed metal length L2 of the first extension line950 for tension balance is substantially equal to a first exposed metallength L1 of the first signal line 940, and the second exposed metalwidth W2 of the first extension line 950 is substantially equal to thefirst exposed metal width W1 of the first signal line 940 within theopening 932 of the solder mask layer 930. In another embodiment, thesymmetrical axis 901 is the middle line crosses through the opening 932along the Z axis. The first extension line 950 and first signal line 940are exposed in the different side of the symmetrical axis 901, but notlimited to it. For example, the symmetrical axis 901 is the diagonalline crosses through the opening 932.

Furthermore, light-emitting diode leads 962 of the light-emitting diode960 can be V-shaped leads, U-shaped leads or I-shaped leads to be fixedon the first signal line 940 and the first extension line 950. Inaddition, the printed circuit board (PCB) 910 can further has a secondsignal line 942 to fix with the light-emitting diode leads 962 of thelight-emitting diode 960. The first extension line 950 can be formed bya plurality of first extension strips and the second exposed metal widthW2 of the first extension strips of the first extension line 950 fortension balance within the opening 932 of the solder mask layer 930 issubstantially equal to the first exposed metal width W1 of the firstsignal line 940 within the opening 932 of the solder mask layer 930.Further, the first signal line 940, the first extension line 950 and thefirst extension line 850 are coplanar.

As is understood by a person skilled in the art, the foregoing preferredembodiments of the present invention are illustrative of the presentinvention rather than limiting of the present invention. It is intendedthat various modifications and similar arrangements be included withinthe spirit and scope of the appended claims, the scope of which shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar structures.

1. A light emitting diode light bar, comprising: a printed circuit board(PCB), wherein the printed circuit board further comprises: a solderingpad formed on the printed circuit board, the soldering pad comprising afirst side and a second side opposite to the first side; a first signalline connecting to the first side of the soldering pad; a firstextension line connecting the second side of the soldering pad; and aprotective layer formed above the first signal line and the firstextension line, the protective layer having an opening to expose thesoldering pad, a portion of the first signal line and a portion of thefirst extension line, wherein the first signal line has a first exposedlength and the first extension line has a second exposed length, thesecond exposed length is substantially equal to the first exposedlength; and a light-emitting diode fixed on the soldering pad.
 2. Thelight emitting diode light bar of claim 1, wherein the first extensionline is aligned with the first signal line.
 3. The light emitting diodelight bar of claim 1, wherein the first signal line has a first exposedwidth and the first extension line has a second exposed width, whereinthe second exposed width is substantially equal to the first exposedwidth.
 4. The light emitting diode light bar of claim 1, wherein thefirst signal line and the first extension line are coplanar.
 5. Thelight emitting diode light bar of claim 1, wherein the first signal lineand the first extension line are collinear.
 6. The light emitting diodelight bar of claim 1, wherein the printed circuit board furthercomprises: a second signal line connected to a third side of thesoldering pad, wherein the second signal line has a third exposedlength; and a second extension line connected to a fourth side of thesoldering pad opposite to the third side, wherein the second extensionline has a fourth exposed length, and the fourth exposed length issubstantially equal to the third exposed length.
 7. The light emittingdiode light bar of claim 6, wherein the second signal line is verticalto the first signal line.
 8. The light emitting diode light bar of claim6, wherein the second extension line is aligned with the second signalline.
 9. The light emitting diode light bar of claim 6, wherein thesecond signal line has a third exposed width, and the second extensionline has a fourth exposed width, and the fourth exposed width issubstantially equal to the third exposed width.
 10. The light emittingdiode light bar of claim 6, wherein the second signal line and thesecond extension line are coplanar.
 11. A backlight module, comprising:a light emitting diode light bar, wherein the light emitting diode lightbar comprises: a printed circuit board (PCB), wherein the printedcircuit board further comprises: a soldering pad formed on the printedcircuit board, the soldering pad comprising a first side and a secondside opposite to the first side; a first signal line connected to thefirst side of the soldering pad; a first extension line connected to thesecond side of the soldering pad; and a protective layer formed on thefirst signal line and the first extension line, the protective layerhaving an opening to expose the soldering pad, a portion of the firstsignal line and a portion of the first extension line, wherein theportion of the first signal line has a first exposed length and theportion of the first extension line has a second exposed length, whereinthe second exposed length is substantially equal to the first exposedlength; and a light-emitting diode fixed on the soldering pad; a lightguide plate disposed adjacent to the light emitting diode light bar; anda reflector disposed under the light guide plate.
 12. The backlightmodule of claim 11, wherein the first extension line is aligned with thefirst signal line.
 13. The backlight module of claim 11, wherein theportion of the first signal line has a first exposed width and theportion of the first extension line has a second exposed width, whereinthe second exposed width is substantially equal to the first exposedwidth.
 14. The backlight module of claim 11, wherein the first signalline and the first extension line are coplanar.
 15. A light emittingdiode light bar, comprising: a printed circuit board (PCB), wherein theprinted circuit board further comprises: a first signal line; a firstextension line; and a protective layer formed above the first signalline and the first extension line, the protective layer having anopening to expose a portion of the first signal line and a portion ofthe first extension line, wherein the portion of the first signal lineis symmetrical to the portion of the first extension line with asymmetrical axis; and a light-emitting diode fixed on the first signalline and the first extension line.
 16. The light emitting diode lightbar of claim 15, wherein the first signal line has a first exposed widthand the first extension line has a second exposed width, wherein thesecond exposed width is substantially equal to the first exposed width.17. The light emitting diode light bar of claim 16, wherein the firstextension line is formed by a plurality of extension strips.
 18. Thelight emitting diode light bar of claim 15, wherein the first signalline and the first extension line are coplanar.
 19. The light emittingdiode light bar of claim 15, wherein the first signal line has a firstexposed length and the first extension line has a second exposed length,the second exposed length is substantially equal to the first exposedlength.
 20. The light emitting diode light bar of claim 15, wherein alead of the light-emitting diode is a V-shaped lead, a U-shaped lead oran I-shaped lead.